There is a major effort in the telecommunication industry to add broadband video services to the telephone network. For technical and economic reasons, the transmitted video will most likely be in digital form, requiring a rate of over 100 Mb/s. Since this high information rate is a thousand-fold greater than that of digitized voice, it will require techniques that emphasize high-speed performance.
Although optical switching has great switching speed potential, the technology has not matured enough to permit deployment. Consequently, electronic switching will be utilized in the first introduction of broadband video. Unfortunately, conventional electronic space switches experience diminished switching speed as the array size increases due to the proportional increase in capacitive loading. One matrix which addresses this problem of speed degradation is shown in FIG. 1, where a KxJ switching array is designed so that each crosspoint switch drives only one other crosspoint switch in the array.
Since the delay from input to output in FIG. 1 is a function of the path traversed by the signal, where the shortest path is from Row K to Output 1 and the longest path is from Row 1 to Output J. the array has the undesirable effect of having the inputs appear at the respective outputs with varying delays. Furthermore, the output logic polarity is non-uniform due to the even and odd numbers of stages present in the array. As a result, circuitry which receives and utilizes the output signals from the switching array of FIG. 1 requires additional control circuitry to compensate for the variable delays and non-uniform output polarities.